A Uniform Resource Identifier is a special case of a Uniform Resource Name that allows an item to be uniquely named and also provides a mechanism for that item to be retrieved.

In support of WIS, WMO is operating a URI system that allows unique identifiers to be issued to items and retrieved by a URL. It is intended that these identifiers will be persistent (that is, will always be associated with the item) and will always be "resolvable" within the limits of the available technologies.

Reference documents to suport WIS management

This series of WMO WIS URIs, the uri:a: series is intended only for documents that support he management of WIS that have to be accessed directly from the URI. It is not suitable for documents that have to be highly available.

In the current series, WMO WIS URIs have the form:

http://wis.wmo.int/uri:a:n

Here the n distinguishes the items to be identified.

Instructions on how registered users can allocate a URI in the uri:a: series can be found here.